This is a note to let you know that I've just added the patch titled
ARM: avoid faulting on qemu
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-avoid-faulting-on-qemu.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3aaf33bebda8d4ffcc0fc8ef39e6c1ac68823b11 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Date: Mon, 27 Nov 2017 11:22:42 +0000
Subject: ARM: avoid faulting on qemu
From: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
commit 3aaf33bebda8d4ffcc0fc8ef39e6c1ac68823b11 upstream.
When qemu starts a kernel in a bare environment, the default SCR has
the AW and FW bits clear, which means that the kernel can't modify
the PSR A or PSR F bits, and means that FIQs and imprecise aborts are
always masked.
When running uboot under qemu, the AW and FW SCR bits are set, and the
kernel functions normally - and this is how real hardware behaves.
Fix this for qemu by ignoring the FIQ bit.
Fixes: 8bafae202c82 ("ARM: BUG if jumping to usermode address in kernel mode")
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Cc: Alex Shi <alex.shi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kernel/entry-header.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -295,7 +295,7 @@
mov r2, sp
ldr r1, [r2, #\offset + S_PSR] @ get calling cpsr
ldr lr, [r2, #\offset + S_PC]! @ get pc
- tst r1, #0xcf
+ tst r1, #PSR_I_BIT | 0x0f
bne 1f
msr spsr_cxsf, r1 @ save in spsr_svc
#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
@@ -327,7 +327,7 @@
ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
ldr lr, [sp, #\offset + S_PC] @ get pc
add sp, sp, #\offset + S_SP
- tst r1, #0xcf
+ tst r1, #PSR_I_BIT | 0x0f
bne 1f
msr spsr_cxsf, r1 @ save in spsr_svc
Patches currently in stable-queue which might be from rmk+kernel@xxxxxxxxxxxxxxx are
queue-4.4/arm-avoid-faulting-on-qemu.patch
queue-4.4/arm-bug-if-jumping-to-usermode-address-in-kernel-mode.patch